Subgrade material - effective resilient modulus

The subgrade material is characterised by the elastic or resilient modulus, Mr, determined by AASHTO T 307 (2007) (also see Section 1.9.1). This property changes with seasonal variation of moisture content. The seasonal resilient moduli must be determined and from that an effective subgrade resilient modulus must be established. 

Having determined the relative damaging factor for each Mr value, the average value of % is calculated and from that the effective resilient modulus, using the above equation. 

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